Every March 14, classrooms around the world shift their focus to math as they celebrate International Pi Day. EducationWorld offers the following classroom activity ideas that teachers can use for a variety of subjects and grades.
For the uninitiated, pi (or π) is a mathematical constant used to numerically represent the ratio of a circle’s circumference to its diameter. Because it’s an irrational numeric constant, pi’s decimal representation never ends and never falls into a permanent, repeating pattern. The constant is most commonly expressed as the rounded number 3.14, and scientists and mathematicians rarely express π beyond 40 digits.
Language Arts: Write a Pi Story or Poem
English teachers can use the number as a unique mathematical writing prompt. Choose a decimal-place limit for π (access online and display on a large screen the digits of pi, or print out a copy of the digits for each student). Then have students compose a story using words that have the same number of letters as each digit in π. For example, since pi begins with the digits 3, 1 and 4, the first word in the story would contain three letters; the second word would contain one letter; the third word would contain four letters, and so on.
It can be very challenging to compose a thought when only words of a certain length can be used, and teachers will be surprised to see how creative students can get with this exercise. The activity also can be used to compose a haiku or other short poem, perhaps even one about the concept of pi.
Art: Make Pi Necklaces
Making beaded necklaces is a common craft activity, but add numbered beads, and you’ve got an instant Pi Day celebration. Purchase numbered beads (example here), or provide nine different colors of beads and use each color to represent a particular digit from 1 to 9. Students should string the beads, being careful to place them in the proper order to represent the digits of pi. Once students finish their necklaces, they can compare them to see who managed to display the most decimal places.
Elementary Classroom: Make “Pi” Plates
Elementary classrooms may not be quite ready to tackle the mathematical and scientific concepts for which π is used, but that doesn’t mean they can’t celebrate the day. Making “pi” plates is an excellent way to introduce the number to students. Using paper plates, have students draw the pi symbol in the center of the plate. Students could also cut π out of construction paper and glue it to the plate.
Using crayons, makers or colored pencils, have them write the digits of π out around the border of the plate. Challenge them to fit as many decimal places as they can while keeping it all legible. You can discuss how pi is important to circles, which just happens to be the shape of the plates.
Math: The Best Deal on Pizza “Pi”
Choose a local pizzeria that offers round pizzas in small, medium and large sizes, and order one of each. Have the students take the radius and find the area of each pizza. Next, have the students divide the cost of each pizza by the area to arrive at the price per square inch. Using the three prices per square inch, kids can accurately determine the best pizza value. Once that question is answered, everyone can eat the pizza.
Physical Education: Super-Size Pi
Feeling ambitious? This activity can involve an entire class or school. Choose one student to stand in the middle of the gym, or in warmer climates, the school sports field. This student will hold one end of a known length of string, and a second student will walk the other end of the string around to form a circle, placing the remaining students evenly to form the circle’s circumference.
When finished, students should represent a nice and round—albeit large—circle. Use a tape measure (or measuring wheel, if your circle is large enough) to find the diameter, using the center student to help measure through the circle’s center. Finally, measure the circumference and have students calculate for pi.